The subject matter disclosed herein relates to power generation systems and, more particularly, to methods and systems for adaptively controlling steam flow (e.g., operational steam flow) to and/or through a steam turbine in a power generation system.
Some power generation systems, for example certain nuclear, simple-cycle and combined-cycle power plant systems, employ steam turbines in their design and operation. These steam turbines are driven by a flow of steam which rotates a rotor of the steam turbine and thereby creates rotary motion for use and conversion by power generation systems and generators. The flow of steam through the steam turbine is controlled in part by a set of control valves which regulate the rate at which the steam flow is introduced through a compressible steam volume. As steam is compressible in nature, the responsiveness of the steam flow does not immediately correlate to control valve adjustments and as a result there is some lag in system response and performance during valve adjustments. Thus, in these systems, when a position of a control valve is adjusted there is a transitory period through which the actual steam flow rate gradually adjusts from a first steam flow rate (e.g., the flow rate of the system with the first control valve position) to a second steam flow rate (e.g., the flow rate of the system with the adjusted control valve position). To account for this lag in steam flow adjustment and to prevent over response/undershooting by the control valves, control systems typically rate limit movements of the control valves, adjusting valve position in a smooth progressive fashion. However, these rate limited movements may lead to inefficient operation, prolonged valve adjustments, lags in system response, a lack of system versatility, delayed output adjustments, and limited operational applications (e.g., steam turbine use in island mode operations).